1. Field
The invention is in the field of folding, room-dividing doors which serve as fire doors in case of fire.
2. State of the Art
It is common practice in many public buildings, such as churches and hotels, to use folding doors as room dividers. In open, folded condition, the doors fit out of the way into compartments in a wall of a large room, and are extended across the room when division of the large room into smaller rooms is desired. While initially such doors were used merely as dividers, some are now constructed to meet certain fire resistant specifications and can be used as fire doors in buildings. Recently, such doors have begun to be used primarily as fire doors in condominiums, apartment and office building lobbies. When used as fire doors, the doors are normally open and when a fire is sensed, are motor driven and automatically close. The doors themselves are not mechanically latched together since they have to remain manually operable for a period of time during a fire to be easily opened by people fleeing the fire. When used as fire doors, if a single door, the leading edge of the lead post assembly of the door generally fits into a receiving recess at the opposite side of the room from where the door is stored. If double or biparting doors, a section of the door is stored on each of opposite sides of a room and the door comes together intermediate the sides of the room. In such instance, one door section has the normal male leading edge on its lead post assembly which fits into a receiving female recess in the lead post assembly of the other door section. While the fire doors themselves are constructed and insulated so that with a fire on one side of the door, the opposite side of the door remains cool, the lead post assemblies of such doors are generally constructed of a single metal channel or of metal pieces connected directly together along large contact areas such that heat is readily transmitted from one side of the lead post assembly to the other causing the entire lead post assemblies to get very not. This is undesirable since all exposed parts of the door on the side opposite the fire preferably should remain cool. Further, with biparting doors, while the seal between the door sections is tight initially, since the doors are not mechanically latched together, after being subjected to intense fire heat of a period of time, the lead post assemblies tend to warp and the doors come apart. This is not acceptable under many fire codes.